(1) Field of Invention
Tumbling media, finishing media, or finishing "chips" for use in the finishing of parts or workpieces by intimate contact therewith in a finishing chamber according to centrifugal, vibratory, gyratory, or rotatory motion, or combinations thereof; production of such finishing media or chips; apparatus for production thereof; method for the production thereof.
(2) Prior Art
The mechanical finishing industry utilizes a wide variety of tumbling media, finishing media, or finishing "chips," in a multitude of shapes and forms, for the surface refinement and/or deburring of parts of workpieces which are usually of metal or plastic. The procedures employed for such surface refinement include centrifugal, vibratory, gyratory, and rotational procedures, and combinations thereof. In the initial stages of the development of the finishing art, such media included natural or synthetic stone, porcelain, abrasive filled clays, wood, leather, plastics, and the like. Ceramics have been popular in recent years, but are gradually being replaced by resin-bonded media due to cost factors. Whatever the type of finishing media employed, the parts to be refined or deburred are generally placed in a suitable finishing chamber together with the finishing media, which is of loose particulate nature, supports the parts, prevents undue collision thereof, and carries or supplies the abrasive which performs the surface finishing or deburring. Incorporation of the particulate abrasive material into a resin binder has become popular because the size and shape of the finishing chip can, in such case, be varied widely to suit individual requirements for dimensions, hardness, and the like, not only of the resin binder but also of the abrasive material incorporated therein. Precisely uniform shapes are attainable in the production of such media, but high-density chips, free of air bubbles, having minimum flash, and which are readily mass produced and simply and completely ejected from the mold in which made with a minimum of labor, for obvious purposes of economy, have not heretofore been available. Up until the present time, resin-bonded finishing chips have usually been individually cast or molded, with obvious disadvantages. Procedure for the production of ceramic or polymeric media by drop-wise feeding of thixotropic compositions from an orifice and thereafter hardening the same has been provided according to the procedure of U.S. Pat. No. 3,549,341, which goes into great detail concerning previous methods and disadvantages thereof. A continuous method of making abrasive finishing media or chips is also disclosed in U.S. Pat. No. 3,503,725, which involves the movement of gelatinous or uncured finishing material along a moving web, cutting the mass into suitable segments, and curing the individual segments to produce abrasive chips. Although both of these methods provide advantages over prior art procedure involving the individual molding or casting of pastelike ceramic or resin-bonded abrasive compositions, they still leave much to be desired from the standpoint of economy, flash reduction, elimination of air bubbles, and mass production of high-quality chips in a simple and convenient manner. Alternative existing procedure for the molding of finishing chips suffers from even greater disadvantages of excessive flash, excell labor costs, and incomplete ejection from the mold wherein produced. It is obvious that a simpler, more expeditious, and more economically-feasible method of mass producing finishing chips would be highly desirable and advantageous to the finishing industry. Such is provided according to the method and apparatus of the present invention, whereby high-density finishing chips, free of air bubbles and having a minimum of flash, may be readily mass produced and simply, completely and automatically ejected from the mold in which made with a minimum of labor and with a maximum of economy.